All references, including any patents or patent applications, cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents forms part of the common general knowledge in the art, in Australia or in any other country.
Bacterial, fungal and protozoal pathogens are responsible for a very wide variety of infections, ranging from minor respiratory ailments to fulminant systemic infections and chronic illnesses. Food poisoning caused by organisms such as Salmonella or Campylobacter is common, and is often associated with endemic infection in livestock or poultry raised using intensive animal husbandry techniques.
Despite the wide availability of antibiotics, control of infection is difficult, and many organisms have the ability to develop resistance. Many microorganisms cause problems which have hitherto proved to be quite intractable, such as multi-drug resistant Staphylococcus aureus infection in hospitals, drug-resistant Enterococcus infections, bacterial, fungal and protozoal infection in HIV patients, tuberculosis, and malaria and other endemic infections in underdeveloped countries.
Currently there are only very few agents which have a wide spectrum of activity against pathogens of bacterial, fungal and protozoal origin. Antibiotics are the most widely used agents in the fight against pathogenic microorganisms. However, most antibiotics have narrow specificity. Even broad spectrum antibacterial antibiotics are not very effective against fungi and protozoa. Most antibiotics belong to a restricted range of classes of compounds; although improved semi-synthetic derivatives of these have developed, only a few new antibiotic compound classes have become available in the last twenty years.
The choice of agents for protection of living organisms against radioactive radiation is also quite limited. Among the radiation protectors the most effective are sulphur-containing compounds (Kuna, 1989). For example, cystamine is approved for use as a radiation-protective agent (Vladimirov et al, 1989). The index of protection of this preparation does not exceed 1.45, and has the disadvantage that it causes diarrhoea. Another known radiation-protective preparation is mercamine (β-mercaptoethylamine) (Mashkovskiy, 1986).
This has a low therapeutic index, short period of action (0.5-1 h), and short duration of radiation protecting activity (15-30 min).
It is known that β-nitrostyrene and some of its derivatives demonstrate biological, and partly fungicidal activity (Foyer, 1973). Russian Patent No. 2145215 showed that certain derivatives of arylnitroalkenes have antimicrobial, antifungal, antiprotozoal activity, and are able to provide protection from radiation damage. These compounds have the following formula
                in which R1′ is H or CH3; and        R2′ and R3′ are the same or different and are selected from H, OCH3, OH, NO2 and (CH3)2N.        
The activities of these compounds are satisfactory, but there is a need for low cost, low-toxicity agents with a wide spectrum of antimicrobial activities.
We have now found that certain substituted nitrostyrene compounds have excellent activity against very wide spectrum of organisms, including bacteria, fungi and protozoa and also have the ability to provide protection from radiation damage.